Pre-CAR-HEMATOTOX at Leukapheresis Predicts Delayed Platelet Recovery After Idecabtagene Vicleucel in Multiple Myeloma.

BACKGROUND

The CAR-HEMATOTOX score has been associated with hematologic toxicity after chimeric antigen receptor T-cell therapy, but it is usually assessed shortly before lymphodepletion, when hematopoietic reserve may already be affected by bridging therapy. We investigated whether the CAR-HEMATOTOX score assessed at leukapheresis, before bridging therapy initiation (Pre-CAR-HEMATOTOX), could predict delayed platelet recovery after idecabtagene vicleucel (ide-cel) in relapsed/refractory multiple myeloma.

PATIENTS AND

METHODS

We conducted a single-center retrospective cohort study of consecutive patients with relapsed/refractory multiple myeloma who underwent leukapheresis and subsequently received ide-cel between November 2022 and March 2026. The primary endpoint was time to platelet recovery to ≥ 100 × 109/L without platelet transfusion or thrombopoietin receptor agonist support. Secondary endpoints included time to platelet recovery to ≥ 75 × 109/L, time to neutrophil recovery to ≥ 1.0 × 109/L without granulocyte colony-stimulating factor support, and platelet transfusion burden.

RESULTS

Among 96 patients, median time to platelet recovery to ≥ 100 × 109/L was significantly shorter in the Pre-CAR-HEMATOTOX low group than in the high group (1.8 vs. 15.8 months, P < .001). Similar findings were observed for recovery to ≥ 75 × 109/L (1.3 vs. 6.3 months, P = .005). High Pre-CAR-HEMATOTOX remained independently associated with delayed platelet recovery in both the primary and exploratory multivariable models. High Pre-CAR-HEMATOTOX was also associated with greater platelet transfusion burden. In contrast, intensive BT, rather than Pre-CAR-HEMATOTOX, was independently associated with delayed neutrophil recovery.

CONCLUSIONS

Pre-CAR-HEMATOTOX assessed at leukapheresis predicted delayed platelet recovery after ide-cel and may support early risk stratification before BT selection.